Circuit with an opto-electronic display unit

ABSTRACT

A circuit provided with an optoelectronic display unit. For discrete display of the settings of a regulating/control unit, said circuit comprises at least one detection element for detecting the actuation of an object in order to modify the settings of the regulating/control unit, whereby the detection element delivers an output signal corresponding to the desired modification. Several luminous diodes ( 1   a   , . . . , 1   n ), which are essentially arranged next to each other in a row and which emit luminous radiation, are used as display elements. A control device controls at least one of the luminous diodes ( 1   a   , . . . , 1   n ) according to the output signal in order to display the respective setting, in addition to the regulating/control unit for modification of the setting. In order to produce a quality display and operator unit, at least two receiver elements which are sensitive with respective to the luminous radiation of the luminous diodes ( 1   a   , . . . , 1   n ) are provided, acting as detection elements in order to detect the luminous radiation reflected by at least one luminous diode ( 1   c ) and by an object ( 2 ), and the control device controls at least one of the luminous diodes in addition to the regulating/control unit as a result of the output signal, which is formed according to the movement of the object relative to the luminous diode ( 1   c ) emitting luminous radiation, according to the movement of said object.

REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the priority of the German patentapplication 101 46 996.9, filed on 25.09.2001, the disclosure content ofwhich is hereby expressly also made the subject matter of the presentapplication.

FIELD OF THE INVENTION

[0002] The invention relates to a circuit comprising an optoelectronicdisplay unit.

BACKGROUND OF THE INVENTION

[0003] In the field of operator control elements, displays formed e.g.by a series of LEDs are known, which indicate a set value. This may be arow of LEDs, i.e. light-emitting diodes, which are arranged side by sideand of which one element emits light and indicates an actual value. As arule, the luminescent elements arranged in a row are suitably labelledto enable an association with a quantity such as e.g. a display in “dB”for volume control. Changeover to another value is effected mechanicallye.g. by means of momentary-contact switches. Generally, to increase andreduce the value one mechanical momentary-contact switch is used in eachcase. A change of value effected by pressing the appropriatemomentary-contact switch is indicated by the appropriate LED in the rowby virtue of a positional variation in the display.

[0004]FIG. 1 shows such an LED display known from the prior art, whereinthe position of the LED and hence also e.g. the “volume level” may beadjusted by means of the plus and minus keys. The advantage of such anarrangement lies in the clear overview of the set position and in thespontaneous operator controllability. The drawback is, however, the needfor mechanical cutouts in the operator control panel and the provisionof appropriate keys.

[0005] From DE 43 36 669 C1 a touch panel is known, comprising opticalsensors, which are associated with different actuating surfaces andreact to the shading of a sensor surface corresponding to the size of afinger. The acquisition of the ambient light is therefore theinformation to be processed. Usually, for this purpose, a means otherthan the means used to generate a light signal is used. For indicating avalue that is to be displayed an additional lighting display unit isrequired. The opto-receivers and opto-transmitters may be operatedexclusively in a pulsed manner, which is disadvantageous for thediscrete alteration of a value that is to be set (cf. also DE 40 07 971A1 in the infrared range).

[0006] The acquisition of information, which is needed to vary a valueto be set at an operator panel, may also be effected by means oftouch-sensitive switching devices according to DE 694 19 735 T2 or DE 3685 749 T2, which through the acquisition of a capacitance correspondwith the optical display unit to be operated; because of its sensitivityto moisture, however, this use is restricted to specific areas.

[0007] DE 39 32 508 A1 shows a conventional reflection light barrierwithout a discrete control facility. Transmitters and receiving elementsalways have to be provided separately. DE 28 24 399 A1 discloses anoptical switch with separate transmitters and receivers. In both cases,the light barriers formed thereby are only the means of setting thedisplay and not the display means itself.

[0008] From U.S. Pat. No. 5,327,160 a touch fader as a remote control isknown, which may be operated only in the switching mode.

[0009] Arrangements of light-emitting diodes, which may be used in turnboth as a light-emitting and as a light-receiving element and theoptical signal of which directly reproduces the value to be displayed,which may moreover be controlled so as to follow the movement of afinger or of a comparable body in order thereby to reach the value to beset, but which may also be operated in clocked manner and thusspontaneously, are not known from the prior art.

SUMMARY OF THE INVENTION

[0010] Proceeding from this background art, an advantage of one or moreof various embodiments of the invention is to provide an advantageousdisplay- and operator control unit and, for operator control of such aregulating/adjusting unit, to utilize the display itself as an operatorcontrol element, wherein both discrete regulation of values to be setand clocked handling is possible.

[0011] In an exemplary embodiment, a circuit with an optoelectronicdisplay unit for the discrete display of the setting of aregulating/adjusting unit includes: at least one detection element fordetecting the actuation of the regulating/adjusting unit by means of abody for changing the setting of the regulating/adjusting unit, whereinthe detection element upon actuation supplies an output signalcorresponding to the desired change; a plurality of light-emittingdiodes disposed substantially side by side in a row and emitting opticalradiation, the light-emitting diodes being formed as display elements ofthe display unit; a control device, which in dependence upon the outputsignal produced by the detection element controls at least one of thelight-emitting diodes to display the respective setting as well as theregulating/adjusting unit to change the setting; wherein the controldevice controls at least one of the light-emitting diodes, the detectionelements as well as the regulating/adjusting unit to follow the movementof the body on the basis of the output signal, which is formed independence upon the movement of the body relative to the light-emittingdiode that is emitting optical radiation, and that either at least tworeceiving elements are provided, which are sensitive to the opticalradiation of the light-emitting diodes and which as the detectionelements detect the optical radiation emitted by at least onelight-emitting diode and reflected by the body, or that at least onereceiving element is provided, which is sensitive to the opticalradiation of the light-emitting diodes and which as the detectionelement detects the optical radiation emitted by at least twolight-emitting diodes and reflected by the body, wherein in both casesthe control device, as soon as the control device because of the outputsignal advances the display unit in one direction to one of the nextlight-emitting diodes, also advances in the same direction the receivingelement(s) being adjacent to the light-emitting diode emitting theoptical radiation.

[0012] With the display unit formed by the light-emitting diodesreceiving elements are associated in such a way that no separatemechanical keys are necessary. For operator control of such aregulating/adjusting unit, therefore, the display itself becomes theoperator control element. There is therefore no need for either keys orcutouts for such keys. This, on the one hand, reduces the cost ofmanufacturing such an operator control unit and, on the other hand,enables the regulating/adjusting unit to be disposed under a closed,protective surface so that it—easy to clean and insensitive to dirt—hasa long useful life and may be used for many applications.

[0013] In another exemplary embodiment, the light-emitting diodes arenot only a display element but temporarily in turn a transmitting andreceiving element, thereby making it possible further to reduce thecircuit engineering outlay.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The invention is described in detail below with reference to theaccompanying drawings. The drawings show:

[0015]FIG. 1 a regulating/adjusting unit according to prior art,

[0016]FIG. 2 a block diagram of a regulating/adjusting unit according toprior art,

[0017]FIG. 3 a diagram for selection of an LED as a display- andoperator control element,

[0018]FIG. 4 a reflecting element usable for operator control above anLED row,

[0019]FIG. 5 an arrangement for realizing a sensitive LED row,

[0020]FIGS. 6, 7 the circuit according to the invention,

[0021]FIGS. 8a-8 e signal characteristics during momentary contact withan LED,

[0022]FIG. 9 a circuit for selection of an outer-lying LED,

[0023]FIG. 10 phases and amplitude relationship of the analogue outputsignal S17 of the comparator 16,

[0024]FIG. 11 the analogue output signal S17 over time duringchangeover,

[0025]FIG. 12 a circuit for increasing the changeover reliability,

[0026]FIGS. 13, 14 the analogue output signal S17 over time across theoutput of the buffer B with and without zero referencing,

[0027]FIG. 15 the signal V1, derived from the analogue output signalS17, over time at the window comparator according to FIG. 14 withassociated LED selection,

[0028]FIG. 16 a circuit according to FIG. 12 with a hysteresis detector,

[0029]FIG. 17 a signal characteristic of the output signal S17 withsimultaneous use of the hysteresis detector,

[0030]FIGS. 18a-18 c arrangements for use as a volume control, forprocessing a data stream or as a position display,

[0031]FIG. 19 a mechanical sliding control according to prior art,

[0032]FIGS. 20, 21 arc-shaped and circular regulating/adjusting unitsaccording to the invention,

[0033]FIG. 22 a regulating/adjusting unit in the form of a virtualturning knob,

[0034]FIG. 23 a regulating/adjusting unit with two transmittingelements,

[0035]FIG. 24 a complete block diagram.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0036] The invention is described in detail below with reference to theaccompanying drawings. However, the embodiments are merely examples,which do not restrict the inventive concept to a specific arrangement.

[0037] In the prior art, the switching assignment for an adjusting unitaccording to FIG. 1 comprises according to FIG. 2 a counting device 91,the instantaneous state of which is determined by the key functions T1(e.g. +key) and T2 (e.g. −key). Each time the keys T1 and T2 areactuated, the counting device 91 counts one value increment upwardsand/or downwards and passes this information on to the display driver92, which allows the LED corresponding to the set value to emit light.Parallel thereto, the set value is passed on to the control apparatusand/or the value regulator 93. This value regulator 93 regulates e.g.the amplitude of an analogue audio signal 94/95 in accordance with theset value 96. Thus, always at least one external control signal T1 or T2is required for setting the value. The LEDs 1 a . . . n merely displaythe set value and have no other function.

[0038] The invention described below dispenses with indirect informationtransfer with the aid of the keys T1 and T2, with the result that theinformation is received up and converted directly by the LED display.

[0039] To achieve this, the bifunctionality of the light-emitting diodesis used: these may emit light, when they are correspondingly driven by acurrent, or produce power and/or current, when they are correspondinglyilluminated. If then, for example, low-crosstalk wiring is selected, alight-emitting diode may be operated sequentially as a transmitter andas a receiver. In principle, the same function is however realizablealso by using alternative receiving elements such as e.g. photodiodesparallel to the light-emitting LEDs. In this case too, because of theoverall size the display is still simultaneously the operator controlelement, even when the light-emitting diodes do not have the abovedouble function.

[0040]FIG. 3 shows such wiring, where the light-emitting diodes (LEDs)operate sequentially in respect of time as transmitters and receivers.In the phase t_(x) the switch Sa, for example, is closed and connectsthe output of the clock generator 100 to the LED via the series resistorR₁₀. The clock generator is operated e.g. at a frequency of 10 kHz. Inthis phase the switch Sb is open and disconnects the LED from theamplifier 300. The inverter 200 is used only to invert the controlsignal Sts. In phase t_(y) the switch relationship is reversed and theswitch Sa disconnects the LED from the clock generator 100, while switchSb connects the LED to the amplifier 300.

[0041] To present a display, generally at least one element of an LEDrow will emit light, while all of the others are switched off.Naturally, there are however also constructions where all of the displayelements up to the set value are switched on, i.e. form a light strip.If the light-emitting element of the LED row emits its light, not asconstant light by virtue of continuous selection, but in a pulsed mannere.g. by means of a 10 kHz rectangular-pulse signal, it neverthelessappears to the naked eye as a continuously light-emitting element. Atthe same time, it may however be used as a transmitting element of asensor apparatus. Adjacent LEDs, which are correspondingly connected asreceivers, may namely receive the signal of the pulse-controlled LEDwhen a reflecting element, e.g. a finger 2, is situated above the LEDthat is emitting the pulsed light.

[0042] Given a positioning of the reflecting element centrally above thetransmitting LED 1 c according to FIG. 4, the emitted light is reflecteduniformly onto the adjacent LEDs 1 b and 1 d. In said case, a pane 37,which is translucent with regard to the respective radiation emitted bythe LED may also be situated between the LEDs and the reflectingelement, e.g. a finger 2. As radiation, in particular, all opticalradiation in the visible range but also in the range invisible to thehuman eye is suitable. Given symmetrical reflection, there is alsoacross the outputs of the amplifiers 5 and 6 an amplitude of equal sizein the output signals 7, 8.

[0043]FIG. 5 shows an arrangement for realizing the sensitive LED row.The light-emitting diodes 1 a . . . 1 n may be utilized both in thetransmitting and in the receiving range. For the transmitting mode ofthe light-emitting diodes 1 a . . . 1 n, connectable driver stages 3 a .. . 3 n are provided and, for the receiving range, connectableamplifiers 2 a . . . 2 n are provided. The signal distribution stages 44and 45 are suitably positioned by the setting of the position counter23. The direction decision unit 47 detects the direction of motion ofthe reflecting element and decides when a specific value of the positiondeviation has occurred. If this was the case, position counter 23 iscorrespondingly activated and counts one position value upwards ordownwards. At the same time, the direction decision unit 47 may first ofall establish whether there was “momentary contact” of thelight-emitting element before reacting to movement e.g. of the finger 2,or whether it was a case of inadvertent touching of the sensor-activesurface and hence no reaction of the LED display is to occur.

[0044] The position counter 23 via a control unit 24 (FIG. 7) controlsboth the selection of the transmitter elements and the receiving mode.In each case, therefore, a single LED is selected as a transmitter,while at least the LEDs adjacent to it—e.g. the next or next but oneLED—are connected as receivers. However, it is of course also possiblefor two LEDs to transmit simultaneously and for the LED disposed betweenthe two light-emitting LEDs to be connected as a receiver. In principle,it is also possible for separate receiving elements to be arrangedstaggered or offset relative to the LEDs, e.g. in a row parallel to theLEDs. At the position counter 23, moreover, the control signal Sts forinfluencing any desired regulating/adjusting unit 30 is tapped.

[0045]FIG. 6 shows a circuit for direction detection, momentary contactrecognition and detection of the horizontal movement of the reflectingelement in relation to the light-emitting LED, here LED 1 c. Here, LED 1c is selected by the clock generator 100 and is emitting light, which isreflected by the finger 2. The adjacent LEDs 1 b, 1 d receive areflection component caused by the finger 2. DCCs 3, 4 form an operatingpoint adjustment for the LEDs as receivers. With the aid of these DCCs(DC compensation), even in the event of intense extraneous light theLEDs are prevented from becoming saturated. The construction of such anoperating point adjustment is known e.g. from DE-PS 44 31117.

[0046] For the sake of simplicity the changeover switches of the LEDselection are not shown in the drawing. Two amplifiers 5 and 6 of anidentical type amplify the low output signals of the LEDs 1 b and 1 dadjacent to the transmitter to a value that is easy to process further.Before both output signals 7 and 8 are combined in the summing stage 10,the inverting circuit 9 inverts one of the two signals.

[0047] Given the absence of a reflecting element, such as a finger 2, orgiven the presence of one but with symmetrical reflection of thetransmitted signal back into LEDs 1 b, 1 d, no signal occurs across theoutput of the summing stage or because of the inverting circuit 9 twosignal components, which for instance arise but are of equal magnitude,cancel each other out so that there is likewise no signal across theoutput of the summing stage 10. Given the presence of a reflectingelement and simultaneous asymmetry relative to the transmitting LED 1 c,e.g. if the finger 2 has shifted slightly to the right, at the LED 1 dowing to intensified reflection a greater signal develops than at theLED 1 b. This leads, across the output of the summing stage 10, to asignal with a clocked modulation with corresponding sign of the phase inrelation to the signal of the clock generator 100. The magnitude of thesignal is determined by the horizontal position of the finger 2 inrelation to the transmitting LED 1 c.

[0048] The output signal of the summing stage 10 is supplied for furtherevaluation to a synchronous demodulator 11. The control signal for thesynchronous demodulator is tapped from the clock generator 100. Itcorresponds substantially to the transmitted signal but takes intoaccount the phase displacements arising in the amplifiers 5 and 6. Thesynchronous demodulator 11 splits the output signal of the summing stage10 once more into two individual signals 12, 13 associated with the LED1 b and 1 d respectively. For a clear decision about the direction ofmotion and/or position of the finger 2 relative to the transmittingelement 1 c, the two individual signals 12 and 13 are compared with oneanother in the comparator 14. The digital output signal S15 of thecomparator 14 provides clear information about the position of thereflecting element, in relation to the transmitting element 1 c, i.e.about whether the finger 2 is situated to the right or left of thecentre of the LED 1 c.

[0049] In order to decide, from which position variation an advancing ofthe light-emitting LED analogous to the movement of the finger 2 is tooccur, the output signals 12 and 13 of the synchronous demodulator 11are compared in a suitably analogue-operating comparator 16, e.g. withan operational amplifier. The analogue output signal S17 corresponds tothe horizontal deviation of the finger from the centre of thetransmitting LED 1 c. From this output signal during further signalprocessing the switching signal for the position counter 23 (FIG. 7) isobtained. The digital output signal S15 is used to define theappropriate counting direction for the position counter 23. In theembodiment, a counting direction towards higher values may advance thetransmission driver from the LED 1 c to the LED 1 d, with a simultaneouschangeover of the amplifiers 5 and 6 from LED 1 b and 1 d to 1 c and 1e.

[0050] To prevent unintended adjustment owing to inadvertent contact,prior “momentary contact” of the light-emitting element for furtheractivation of the adjustment facility may be provided. For this purpose,information has to be obtained from the vertical movement of the finger2 towards or away, respectively, from the light-emitting element. Thisinformation may be gathered from the summing stage 18, in which bothsignals of the receiving LEDs are summed. A synchronous demodulator 19correspondingly evaluates the summed signal and said signal is availablevia the buffer stages 20 as an analogue distance signal S21.

[0051]FIG. 7 shows the evaluation of the signals S21, S15 and S17. Awindow comparator 22 supplies an output signal S22 when the outputsignal S17, which is in fact an analogue value of the horizontalposition of the finger in relation to the transmitting LED, exceeds orfalls below a value preselected in the window comparator 22. This valueis reached when the reflective element, i.e. the finger 2, is moved somedistance laterally of the centre of the transmitting element (LED 1 c)towards the adjacent receiving element (LED 1 b or 1 d), even if thedistance is less than half the distance between two adjacent elements.The output signal S22 of the window comparator 22 is supplied as a clocksignal to the position counter 23.

[0052] The decision, whether the position counter 23 is to count upwardsor downwards, which corresponds to a “shift” of the light-emitting LEDto the left or to the right, is taken from the output signal S15 of thecomparator 14. The output signal S23 of the position counter 23 issupplied to the control unit 24. The control unit 24 determines theposition—corresponding to the numerical value of the output signalS23—of the transmitting LED and its at least two indirectly or directlyadjacent receiving LEDs or receiving elements.

[0053] In principle, the light-emitting LED is not to change positionsimply as a result of a hand being inadvertently wiped over the LED.Rather, first the position sensitivity is to be activated manuallybefore the light-emitting LED “travels along” with the moving finger.For this purpose, the output signals 7, 8 are combined in the summingstage 18 and synchronously demodulated and the distance signal S21 thusobtained is conditioned in a suitable evaluation circuit 25 in such away that e.g. a shift of position is enabled only after “momentarycontact” with the light-emitting LED has been effected once or twice.

[0054] The momentary-contact recognition apparatus preferably recognizesas momentary contact a pattern of motion, which comprises the approachof a body, the sudden braking of the body against a touched surface anda dwelling on the surface for a preselected time t28.

[0055] To this end, in the embodiment the distance signal S21 is passedthrough the high-pass filter 26, which allows through only thehigher-frequency spectral components of the distance signal S21. Thesesignal components occur only in the event of a rapid variation in thedistance signal S21 according to FIG. 8a. The sudden braking of thefinger on a translucent surface above the LED row may therefore lead toan output signal S26, a signal differentiated from the distance signalS21. If this output signal S26 according to FIG. 8b exceeds apredetermined value Ref, the comparator 27 supplies a digital outputsignal S27 (FIG. 8c) to a first timer 28 with a timer time t28 ofseveral hundred milliseconds to seconds (FIG. 8d). At the end of thisshort time, timer 29 according to FIG. 8e is started. Its running timeis several seconds. The output signal S29 enables the position counter23. A variation of the counter content then retriggers (rt) the timer29. If the position of the light-emitting LED is not varied within therunning time t29 of the timer 29, the time t29 elapses and the positioncounter 23 is disabled again. This circuit arrangement prevents theposition of the light-emitting LED in the LED row from being varied byan unintentional movement. It is only after “momentary contact” that theposition of the light-emitting LED may be shifted by renewed contactwith the light-emitting LED and displacement of the finger.

[0056] At this point any conceivable circuit arrangement may beinserted, i.e. including counter arrangements, which also enable theposition counter 23 only after repeated momentary contact with thelight-emitting LED. From WO 01/54277 A1 an arrangement—which is e.g.preferentially usable here—is known, in which a function is switchedonly if a finger quickly touches (has momentary contact with) thetranslucent surface above an LED and remains relatively still there forat least a specific time, e.g. 200 ms.

[0057] The digital output signal S23 of the position counter 23 moreovercontrols the control unit 24. In the control unit 24, the transmitteddrive signal is suitably distributed to the LEDs and the two amplifierinputs of the amplifiers 5, 6 (FIG. 6) are distributed to the LEDsadjacent to the transmitting diodes. The output signal S23 of theposition counter 23 (FIG. 7) may further be used to control any desiredvalue controller of a regulating/adjusting unit 30, e.g. for volumecontrol.

[0058] If the light-emitting LED is “shifted” into one of the two endpositions, it is however no longer possible for the at least twoadjacent LEDs to serve as receivers, but only one. In said case, in theevent of parasitic reflections e.g. at the translucent surface, thesingle receiving LED, e.g. LED 1 a, receives a signal similar to that ofa “shifted” finger. In extreme cases, this unwanted signal would lead tothe selection repeatedly skipping back from LED 1 a to LED 1 b.

[0059] To prevent this, upon selection of LED 1 a a simulated “lightsignal” is presented to the amplifier 6 (FIG. 6). FIG. 9 shows thecorresponding changeover in said respect. Switches S1, S2 and S3 areactivated via the control unit 24 by the control signal S23 of theposition counter 23 (FIG. 7). Switch S1 connects the output of the clockgenerator 100 to the appropriate LED. In the embodiment, in FIG. 9 tothe LED 1 a, i.e. out on the far left. Switch S3 connects the amplifierinput of the amplifier 5 to the LED 1 b lying adjacent on the right.Switch S2 connects the amplifier input of the amplifier 6 to a voltagedivider R₁/R₂, which is connected to the output of the clock generator100. The divider ratio of the voltage divider R₁/R₂ is so dimensionedthat the magnitude of the divided-down transmitted clock signal isslightly greater than the received signal of LED 1 b produced byparasitic reflection at the translucent surface.

[0060] It is thereby guaranteed that, when the finger is moved over theLED row, e.g. from the middle to the left over LED 1 a, the latter asthe last LED in the row emits light. If, on the other hand, the fingeris moved from the side across the light-emitting LED 1 a towards themiddle of the LED row, then in the position of the finger 2 between LED1 a and 1 b the reflection of the transmitting LED 1 a at the fingerwill produce a greater signal than was supplied by the voltage dividerR₁/R₂. The phase angle of the signal S10 (FIG. 6) is therefore reversedand the selection of LED 1 a switches over to LED 1 b, and/or followsthe finger 2.

[0061] With the previously described arrangement for controlling the LEDrow the light may of course be shifted by the finger only in onedirection in each case. The reason for this is that, from a specificdistance—determined by the threshold values defined in the windowcomparator 22 (FIG. 7)—of the finger from the centre of the actuallylight-emitting LED, the light shifts in front of the moving finger 2. Ifby virtue of continuous finger movement the actually light-emitting LEDis passed over again, the light switches in front of the finger to thenext LED and so on. If, however, after a shift the finger 2 stops and ismoved back, the last light-emitting LED remains in its last position. Toreverse the direction of motion, the finger then has to be placed—viewedin the direction of motion—in front of the light-emitting LED. It has tobe passed over in the, then, reverse direction of motion. The displaythen follows the finger position once more.

[0062] However, as this is impractical in general use, between thecomparator 16 (FIG. 6) and the window comparator 22 (FIG. 7) a circuitis inserted, which ensures that the light spot always directly followsthe finger movement. This circuit arrangement utilizes the effectwhereby during the changeover from one LED to the next LED the polarityof the counter control signal (output signal S15) and of the analogueoutput voltage of the comparator 16 (output signal S17) is reversed.This is easy to explain if one considers that the changeover occurs whenthe finger moves e.g. to the right away from the light-emitting LED andthe LED situated on the right of this LED detects an increasedreflection. If this value exceeds a predetermined quantity, then thewindow comparator 22 supplies a corresponding signal and the positioncounter 23 (FIG. 7) counts one value “upwards”, in this case thereforeto the “right”. The originally light-emitting LED “shifts” from the,relative to the finger 2, left position to the position on the right ofthe finger. The LED originally connected as a light-emitting elementchanges its function and becomes the opto-receiver, which is however nowsituated on the left of the transmitting element. However, as the finger2 is still situated in an approximately identical position, the LEDsituated on the left of the transmitting element then receives morereflection than the LED situated on the right of the transmittingelement. This however means, across the output of the summing stage 10(FIG. 6), a reversal of the phase and hence also a reversal of thepolarity of the digital output signal S15 and also of the analogueoutput signal S17.

[0063]FIG. 10 describes the phases and amplitude relationship of theanalogue output signal S17 (FIG. 6) of the comparator 16 in such a case.Position 51 or LED 1 a . . . 1 n, respectively, show the mechanicalarrangement of the LEDs, 52 the associated signal values of the analogueoutput signal S17 of the comparator 16. 53 corresponds in theillustrated case to a signal, when LED 1 c is emitting light. If duringa finger movement to the right the output signal S17 of the comparator16 falls below the preselected lower threshold value US, the positioncounter 23 counts one counter upwards (54 in FIG. 10). The countersetting determines which LED is selected in switching mode (55 FIG. 10).The solid bold line 56 shows the characteristic of the output signal S17of the comparator 16 when a finger 2 is moved from left to right overthe LED row.

[0064] In the changeover situation, the threshold value OS of the windowcomparator 22 is again—in a different polarity—exceeded and so theposition counter 23 will count back again. A continuous changeover ofthe LED positions symmetrically relative to the finger 2 would be theresult. The light-emitting LEDs follow the finger 2 in that, when thefinger is positioned centrally on an LED, only this LED emits light,whereas, when the finger is positioned between two LEDs, both emit lightin rapid alternation.

[0065] For tolerances reasons, however, after a first overshooting ofthe threshold value US a changeover may be effected, after which thethreshold value OS is in turn overshot and a second changeover iseffected back to the original position, only this time the thresholdvalue US is not undershot so that a further changeover is not absolutelyguaranteed. Upon movement of the finger over the LED row the display mayconsequently “become stuck”.

[0066]FIG. 11 shows the analogue output signal S17 (FIG. 6) of theposition recognition comparator 16. In section 61 the finger 2 movesfrom the centre of the transmitting LED e.g. to the right, the analogueoutput signal S17 of the comparator 16 correspondingly increases. Whenit hits the upper threshold value OS, the LED selection advances to thenext LED on the right. The sign of the output signal therefore reverses(62) and the signal reaches the lower threshold value US. The LEDselection switches back to the previous LED. Naturally, there is also acorresponding changeover of the LEDs connected as receivers.

[0067] Undesirable tolerances, e.g. as a result of a scratch on thetranslucent surface, may lead to the situation where the LED does infact “shift”, because the upper threshold value OS was reached withoutdifficulty (63, FIG. 11), but afterwards the lower threshold value USafter the change of sign is no longer undershot (64, FIG. 11). If theoperator in this situation reverses the direction of the finger movementbecause e.g. the operator wishes to move back from this adjusted value,the display does not respond and, despite movement of the finger,remains in position. This maloperation may easily be prevented in thatafter each change of LED the output signal S17 is utilized in its entiremagnitude from zero. Previously, it had to run through the voltage rangefrom the upper threshold value OS, through zero to the lower thresholdvalue US. Upon a second switching operation back to the originalposition there was a factor of uncertainty about reattainment of thelower threshold value US. If, however, the instantaneous output signalS17 of the comparator 16 is referred to “0” at the changeover moment,the Δ of the signal starts at zero and therefore exceeds the respectivethreshold value with double amplitude, which guarantees unconditionalswitching reliability.

[0068] In FIG. 12 a low pass constructed from R₃ and C₃ forms a timedelay for the signal S17 of the comparator 16. Capacitor C₂ togetherwith switch S4 forms a referencing unit. Buffer B is used only toelectrically isolate the referencing unit C₂/S4 from the low pass R₃/C₃.D1 is a differentiating apparatus for a counting signal of the positioncounter 23. Each time the numerical value S23 of the position counter 23changes, a short pulse is applied via a signal line SD1 to switch S4and, when switch S4 is closed, the capacitor C₂ is discharged to zero.The output signal S17 of the comparator 16 because of the delayinglow-pass effect of the low pass R₃/C₃ at the output of the buffer Bduring the switching time of switch S4 has experienced only aninsubstantial change, so that virtually the entire Δ of the outputsignal S17 may come into effect across the input of the windowcomparator 22. Naturally, zero is only one example of a preselected orpreselectable value. Referencing may be effected also to anotherspecific preselected or preselectable value, so that after thechangeover the next threshold value US or OS is reached with part of theoutput signal S17.

[0069] With the circuit according to FIG. 12 it is guaranteed that eachfinger movement is easily detected and the light-emitting LED alwaysfollows the finger movement. In said case, only one LED emits light whenthe finger is situated centrally on it, and two adjacent LEDs when thefinger is situated between them. In the latter case, the position of thelight-emitting LED alternates at a frequency determined by the low passR₃/C₃. Given suitable dimensioning, the frequency may be higher than isdetectable with the eye, so that a continuous emission of light isperceived. Analogously to the finger position between the two LEDs,there is a corresponding distribution of the intensity of theluminosity. In the embodiment, R₃ has 10 kΩ, R₄ 1 MΩ, R₅ 10 kΩ, R₆ 1 kΩand R₇ 10 kω. C₂ has a value of 0.1 μF and C₃ a value of 10 nF.

[0070]FIG. 13 shows the analogue output signal S17 across the output ofthe buffer B (FIG. 12) when a finger is moved over the LED row withoutswitch S4 being actuated. FIG. 14 shows the same analogue output signalS17 only across the input of the window comparator 22, when the switchS4 upon each change of position refers the signal S17 to zero (71 inFIG. 14). The dashed lines 72, 73 correspond to the signal if no furtherchangeover were to occur. It is clear that the output signal S17 afterreferencing 71 would definitely exceed the threshold value OS or US,respectively, and therefore leads to a trouble-free switching operation.The steep flank arises during the referencing 71 when switch S4 for ashort time during the position switching operation discharges thecapacitor to “0”. To prevent the input voltage of the window comparator22 from “drifting away” on account of the open switch S4, a high-valueresistor R4 is connected in parallel to the switch S4. The d.c.decoupling by means of capacitor C₂ and resistor R₄ additionally alsoprevents the influence of disturbances, e.g. an asymmetry across theoutput of the comparator 16 owing to scratches on the translucentsurface. The disturbance-induced signal deviation from zero, when thefinger has been removed, is automatically referenced to zero after thecapacitor C₂.

[0071] Often, however, given a finger position between 2 adjacent LEDs,for easier selection only one of the two LEDs should emit light. Andnamely the one that is nearest to the controlling finger. In thepreviously described embodiment both LEDs emit light alternately,according to the construction so quickly that to the eye it appears likea continuous emission of light. FIG. 15 shows the signal V1, which isderived from the output signal S17, across the input of the windowcomparator 22 in FIG. 12 when the finger 2 is situated between two LEDs.AP shows the activation phases of the two LEDs n and n+1.

[0072] In order in this situation to be able to opt for one of the twoLEDs, by means of a hysteresis detector 84 (FIG. 16) as a decision aid acontrol signal S84 is produced for the two threshold values OS and US.The hysteresis detector 84 checks the count value of the positioncounter 23 (FIG. 7) for periodic counting operations with maximumcounting increments ±1. If such a switching sequence appears in thecount value S23 for a number of periods (e.g. greater than 5) within apredetermined time, the hysteresis detector 84 opens the switch S5. Thisis always the case when a finger is situated between two adjacent LEDs.If switch S5 opens, the capacitor C₅ charges up from the threshold valuepreselected by the voltage divider R₅, R₆, R₇, i.e. towards a higherpotential. In said case, the upper threshold value rises, while thelower threshold value drops.

[0073] The control device 24 therefore switches back and forth betweenadjacent light-emitting diodes, if the finger 2 remains between adjacentLEDs without changing, and increases the sensitivity for positionrecognition until a preselected value is exceeded. Thus, in the event ofrepeated switching back and forth a decision aid is activated, whichsets the receiving element less and less sensitively until thelight-emitting diode situated closer to the body may be clearlydetermined. The decision aid then reverts to the state of sensitivityfor the detection of further movement of the finger 2.

[0074]FIG. 17 shows the variation of the threshold value OS and US. Inthe period t₁ the hysteresis detector 84 has identified at least fiveswitching operations between two adjacent LEDs and has set the controlsignal S84 to “low” so that the switch S5 has been opened. This statelasts until the signal V1 no longer exceeds the threshold values (81FIG. 17) and only one LED emits light. This is registered by thehysteresis detector 84 and it closes switch S5 again. The time constantof the capacitor C₃ and of the resistor R₅ is to be so dimensioned thatit is greater than the time constant of C₂ and R₄ in order to guaranteetrouble-free referencing of the signal V1. The circuit arrangement hasthen reattained its original sensitivity for the detection of fingermovement. The changeover of the threshold values OS and US may beeffected so quickly that a simultaneous emission of light by two LEDsoccurs for only such a short time during the finger movement that it isnot perceived by the eye.

[0075] For improved comfort a circuit may be additionally inserted,which is not more closely designated here and which in the event of aninadvertent displacement of the finger 2 during removal results in noshift of position of the LEDs and hence of the desired control value.For this purpose, the distance signal S21 is evaluated. If thisindicates a removal of the finger with a simultaneous change ofposition, then this change of position is accordingly ignored, e.g. bydisabling the position counter 23. Preferably, a value of the deviationfrom the last signal of e.g. 10% may also be preselected. If this valueis exceeded during removal of the body, the control device 24 selectsthe LED, at which the body last dwelt for longer than a preselecteddwell time, e.g. t28.

[0076] Despite the seemingly comprehensive signal evaluation, atouch-sensitive LED row in the form of an IC (integrated circuit) withexternal LEDs is perfectly easy to realize. Such an arrangement may beused for example, directly as a “volume control”, to process a digitaldata stream or alternatively only to output the “position” (FIG. 18a, b,c). Measures may also be taken so that after disconnection of the powersupply the actual counter content of the position counter 23 is retaineduntil it is activated again. Unlike mechanical sliding controls (FIG.19), which generally comprise a straight sliding region from a point Ato a point B, the touch-sensitive LED row may be realized in any desiredform of presentation, e.g. arc-shaped or round (FIG. 20/FIG. 21). Tolengthen the operating path, LED rows may also be cascaded. Accordingly,if the function of a last LED in a row is functionally linked to a firstLED of the same row, a virtual turning knob may easily be produced (FIG.22).

[0077] The regulating/adjusting unit 30 will generally comprise only onedisplay, i.e. only one light-emitting element. Naturally, however, theprinciple—1 transmitter, 2 receivers grouped at a small or large,uniform or non-uniform distance around the transmitter—may also betransposed. In said case, two transmitters alternately transmit and onereceiver disposed midway between the two transmitters evaluates thereflected signal. Such a circuit arrangement, but without the variationof position required for the touch-sensitive LED row, is described inthe earlier German patent application 101 33 823.6. By virtue ofautomatic correction of the received signal to zero, in theabove-mentioned circuit arrangement potentially disturbing extraneouslight influences are totally avoided.

[0078] In an arrangement with 2 transmitting elements, the finger ispositioned in the “gap” between the two transmitting elements and thenshifted by moving the finger into the desired position. Naturally, heretoo, a “momentary contact” with the “gap” may initially activate afurther shift facility (FIG. 24).

[0079]FIG. 25 shows a complete block diagram of the “touch-sensitive LEDrow”.

[0080] Occasionally, a rapid change of the selected setting of theregulating/adjusting unit may also be desirable. Up until now, what hasmostly been mentioned is a momentary contact with the light-emitting LEDor the gap. It is however also possible for the entire LED row, afteradjustment has been effected, i.e. when, for example, removal of theactuating body has been recognized, to be activated at regularintervals, e.g. at a frequency not visible to the human eye, in order tocheck whether and where a body is approaching or where there ismomentary contact, and there e.g. after momentary contact to take overthe LED as a display and also correspondingly activate theregulating/adjusting unit.

[0081] It is self-evident that this description may be subject to a widerange of modifications, alterations and adaptations, which are in therange of equivalents to the appended claims.

1-25. (Canceled)
 26. Circuit with an optoelectronic display unit for thediscrete display of the setting of a regulating/adjusting unitcomprising: at least one detection element for detecting the actuationof the regulating/adjusting unit by means of a body for changing thesetting of the regulating/adjusting unit, wherein the detection elementupon actuation supplies an output signal corresponding to the desiredchange; a plurality of light-emitting diodes disposed substantially sideby side in a row and emitting optical radiation, the light-emittingdiodes being formed as display elements of the display unit; a controldevice, which in dependence upon the output signal produced by thedetection element controls at least one of the light-emitting diodes todisplay the respective setting as well as the regulating/adjusting unitto change the setting, wherein the control device controls at least oneof the light-emitting diodes, the detection elements as well as theregulating/adjusting unit to follow the movement of the body on thebasis of the output signal, which is formed in dependence upon themovement of the body relative to the light-emitting diode that isemitting optical radiation, and that either at least two receivingelements are provided, which are sensitive to the optical radiation ofthe light-emitting diodes and which as the detection elements detect theoptical radiation emitted by at least one light-emitting diode andreflected by the body, or that at least one receiving element isprovided, which is sensitive to the optical radiation of thelight-emitting diodes and which as the detection element detects theoptical radiation emitted by at least two light-emitting diodes andreflected by the body, wherein in both cases the control device, as soonas the control device because of the output signal advances the displayunit in one direction to one of the next light-emitting diodes, alsoadvances in the same direction the receiving element(s) being adjacentto the light-emitting diode emitting the optical radiation.
 27. Circuitaccording to claim 26, wherein the one direction is along the row oflight-emitting diodes.
 28. Circuit according to claim 26, wherein thereceiving element is one of the light-emitting diodes, which is at leastpart of the time controlled in such a way that upon illumination itgenerates a voltage.
 29. Circuit according to claim 26, wherein thelight-emitting diodes are operated sequentially in respect of time astransmitter and receiving element.
 30. Circuit according to claim 26,wherein the light-emitting diodes immediately adjacent to thelight-emitting diode, which is emitting optical radiation, are operatedas a receiving element, and that, as soon as the control device becauseof the output signal advances the display unit to the nextlight-emitting diode, the adjacent light-emitting diodes operated as areceiving element are also advanced in the same direction.
 31. Circuitaccording to claim 26, wherein the optical radiation emitted by thelight-emitting diode is modulated by a clock generator and thatconnected downstream of the receiving elements is a synchronousdemodulator for recognizing the modulated light reflected by the body.32. Circuit according to claim 26, wherein a momentary contactrecognition apparatus with a surface in the vicinity of thelight-emitting diode is provided, which activates a timer, which enablesthe actuation of the display unit.
 33. Circuit according to claim 32,wherein the light-emitting diodes and the receiving elements form atleast two reflection sections and that, for recognition of the momentarycontact, the individual signals resulting therefrom are supplied to asumming stage to form a signal of the distance from the surface of or inthe vicinity of the surface of the light-emitting diode.
 34. Circuitaccording to claim 32, wherein the momentary-contact recognitionapparatus recognizes as momentary contact a pattern of motion, whichcomprises the approach of the body, the sudden braking of the bodyagainst a momentarily touched surface as well as a dwelling on thesurface for a preselected time.
 35. Circuit according to one of claim32, wherein the momentary-contact recognition apparatus recognizes asmomentary contact only a repeated momentary contact.
 36. Circuitaccording to claim 26, wherein the light-emitting diodes and thereceiving elements form at least two reflection sections and that acomparator compares individual signals resulting therefrom in order todecide about the direction of motion in order to generate a digitaloutput signal.
 37. Circuit according to claim 26, wherein thelight-emitting diodes and the receiving elements form at least tworeflection sections and that a position recognition comparator comparesindividual signals resulting therefrom in order to decide about thechangeover instant between two adjacent light-emitting diodes togetherwith formation of an analogue output signal for the position of theobject.
 38. Circuit according to claim 26, wherein, for a light-emittingdiode located at the end of the row, a simulation circuit simulates alight signal at the side remote from the light-emitting diode, which isadjacent to the light-emitting diode located at the end of the row. 39.Circuit according to claim 38, wherein as the simulation circuit avoltage divider is provided, the divider ratio of which is sodimensioned that the divided-down transmitted clock signal of the clockgenerator at the side, where the light signal is simulated, is at leastslightly greater than the reception signal of the adjacentlight-emitting diode produced by parasitic reflection at the translucentsurface.
 40. Circuit according to claim 26, wherein the control deviceon the basis of the output signals controls the light-emitting diodes insuch a way that the light-emitting diode forming the display element issituated under the body.
 41. Circuit according to claim 40, wherein thecontrol device, when the body remains in an unvarying position betweenadjacent light-emitting diodes, switches back and forth between theadjacent light-emitting diodes, and increases the sensitivity forposition detection until a preselected value is exceeded.
 42. Circuitaccording to claim 41, wherein in the event of repeated switching backand forth a decision aid is activated, which sets the receiving elementless and less sensitively until the light-emitting diode situated closerto the body is selectable and which then reverts to the state ofsensitivity for the detection of further movement of the body. 43.Circuit according to claim 42, wherein the decision aid is a hysteresisdetector.
 44. Circuit according to one of claims 41, wherein the outputsignal at a instant of a changeover is referred to a specificpreselected or preselectable value so that after the changeover a nextthreshold value is reached with a part of the output signal.
 45. Circuitaccording to claim 26, wherein the output signal for the position of thebody is ignored if at the same time a signal of the distance from thesurface of or from the vicinity of the surface of the light-emittingdiode changes with simultaneous removal of the body from thelight-emitting diode.
 46. Circuit according to claim 45, wherein, whenthe output signal for the position of the body during removal varies bymore than a preselected value, the control device selects thelight-emitting diode, at which the body last dwelt for longer than apreselected dwell time.
 47. Circuit according to claim 26, whereinstorage means are provided, which store a last setting even in ade-energized state.
 48. Circuit according to claim 26, wherein aplurality of rows of light-emitting diodes are cascaded in order tolengthen the operating path.
 49. Circuit according to claim 26, whereina last light-emitting diode of the row is functionally linked to a firstlight-emitting diode of the same row with simultaneous formation of avirtual turning knob.
 50. Circuit according to claim 26, wherein thelight-emitting diodes are arranged in the shape of an arc or circle. 51.Circuit according to claim 26, wherein the control device operates allof the light-emitting diodes up to a position of the body and/or up to aposition of the receiving element as display elements to form a lightstrip.